Process to prepare levulinic acid

Abstract

The invention describes processes to prepare levulinic acid, formic acid and/or hydroxymethyl furfural from various biomass materials.

The invention claimed is: 
     
       1. A process to prepare levulinic acid comprising the steps:
 a) heating an aqueous solution of a mineral acid to a temperature from about 60° C. to about 160° C. in a reactor, wherein the mineral acid is present from at least 20 percent by weight to about 80 percent by weight; 
 b) adding a monosaccharide or di-saccharide to the heated aqueous acid in the reactor to form a reaction mixture over a period of time at a rate such that the monosaccharide content of the reaction mixture remains less than or equal to about 5% by weight of the reaction mixture during the entire reaction; 
 c) combining the reaction mixture with a first extraction solvent that is a phenolic or substituted phenolic extraction solvent to create an extraction phase and an aqueous raffinate phase, wherein levulinic acid and optionally, formic acid are in the extraction phase; 
 d) recycling the aqueous raffinate phase to the reactor; and 
 e) washing solids produced in the reactor with water to form a filtrate and combining the filtrate with the aqueous raffinate phase or contacting the filtrate with a second extraction solvent which may be the same or different than the first phenolic or substituted phenolic extraction solvent. 
 
     
     
       2. The process of  claim 1 , wherein the extraction solvent is 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, or a combination thereof. 
     
     
       3. The process of  claim 1 , wherein the phenolic or substituted phenolic extraction solvent is a phenol, an alkylphenol, a xylenol, a methoxyphenol, a cresol, a polydimethylsiloxane, a substituted alkyl phenol, a tertiary amine/alkyl phenol mixture, phenol/alkyl phenol blends with a C5-C36 hydrocarbon or C6-C12 aromatic hydrocarbons, 2-ethyl-hexanoic acid or perfluoro-octanoic acid or perfluoro-octanol or mixtures thereof. 
     
     
       4. The process of  claim 3 , wherein the extraction solvent comprises phenol, 4-methoxyphenol, 2-methoxyphenol, 3-methoxyphenol, 2-sec-butyl phenol, 3-sec-butyl phenol, 4-sec-butyl phenol, 2-t-butyl phenol, 4-t-butyl phenol, 2,4-di-t-butyl phenol, 2,4-di-methoxyphenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-xylenol, 2, 4-xylenol, 2, 5-xylenol, 2, 6-xylenol, 3, 4-xylenol, or 3, 5-xylenol, 4-hexyl-resorcinol, butylated hydroxyl-toluene (BHT), 2,5-dimethoxyphenol, 3,5-dimethoxy phenol, 2,6-dimethoxy phenol, nonylphenol, or mixtures thereof. 
     
     
       5. The process of  claim 1 , further comprising the step of subjecting the extraction phase to a base, an anion exchange resin, or water washing the extraction phase to reduce the amount of mineral acid present to less than or equal to 0.5 weight percent of the extraction phase. 
     
     
       6. The process of  claim 1 , further comprising the step of treating the aqueous raffinate phase with an adsorbent to decrease the amount of the extraction solvent from the raffinate phase. 
     
     
       7. A process to prepare levulinic acid comprising the steps:
 a) heating an aqueous solution of a mineral acid to a temperature from about 60° C. to about 160° C. in a reactor, wherein the mineral acid is present from at least 20 percent by to about 80 percent by weight; 
 b) adding from about 0.15 pounds to about 80 pounds per hour of a monosaccharide or di-saccharide per 100 pounds of the heated aqueous acid in the reactor to form a reaction mixture comprising levulinic acid, wherein the monosaccharide or di-saccharide content remains less than or equal to about 5% by weight of the reaction mixture during the entire reaction; 
 c) combining the reaction mixture comprising levulinic acid with a first extraction solvent that is a phenolic or substituted phenolic extraction solvent to create an extraction phase and an aqueous raffinate phase, wherein levulinic acid and optionally, formic acid are in the extraction phase; 
 d) recycling the aqueous raffinate phase to the reactor; and 
 e) washing solids produced in the reactor with water to form a filtrate and combining the filtrate with the aqueous raffinate phase or contacting the filtrate with a second extraction solvent which may be the same or different than the phenolic or substituted phenolic extraction solvent. 
 
     
     
       8. The process of  claim 7 , wherein the extraction solvent is 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, or a combination thereof. 
     
     
       9. The process of  claim 7 , wherein the phenolic or substituted phenolic extraction solvent is a phenol, an alkylphenol, a xylenol, a methoxyphenol, a cresol, a polydimethylsiloxane, a substituted alkyl phenol, a tertiary amine/alkyl phenol mixture, phenol/alkyl phenol blends with a C5-C36 hydrocarbon or C6-C12 aromatic hydrocarbons, 2-ethyl-hexanoic acid or perfluoro-octanoic acid or perfluoro-octanol or mixtures thereof. 
     
     
       10. The process of  claim 9 , wherein the extraction solvent comprises phenol, 4-methoxyphenol, 2-methoxyphenol, 3-methoxyphenol, 2-sec-butyl phenol, 3-sec-butyl phenol, 4-sec-butyl phenol, 2-t-butyl phenol, 4-t-butyl phenol, 2,4-di-t-butyl phenol, 2,4-di-methoxyphenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-xylenol, 2, 4-xylenol, 2, 5-xylenol, 2, 6-xylenol, 3, 4-xylenol, or 3, 5-xylenol, 4-hexyl-resorcinol, butylated hydroxyl-toluene (BHT), 2,5-dimethoxyphenol, 3,5-dimethoxy phenol, 2,6-dimethoxy phenol, nonylphenol, or mixtures thereof. 
     
     
       11. The process of  claim 7 , further comprising the step of subjecting the extraction phase to a base, an anion exchange resin, or water washing the extraction phase to reduce the amount of mineral acid present to less than or equal to 0.5 weight percent of the extraction phase. 
     
     
       12. The process of  claim 7 , further comprising the step of treating the aqueous raffinate phase with an adsorbent to decrease the amount of the extraction solvent from the raffinate phase.